Logic circuitry for monitoring the cyclic operations of a pair of devices

ABSTRACT

Logic circuitry is utilized to monitor the continued cyclic operation of a pair of devices, e.g., strand-feeding devices. As the devices function a pair of trains of pulses are generated and the logic circuit detects and generates a malfunction signal upon the generation of two pulses within one train without the intervening generation of a pulse in the other train. The logic circuit accepts concurrent generation of pulses, and the subsequent reversal of the lead pulse in the trains without the generation of malfunction signals. Facilities are also provided to allow the devices to commence operation independent of control by the logic circuits.

United States Patent [72] Inventor John ,I. Glosek 3,268,743 8/1966Nourney 328/109 Roselle, NJ. 3,532,994 10/1970 Ferrier, .lr 328/109 3;1' 1970 Primary Examiner-Donald D. Forrer E z 1: 1971 AssistantExaminer-B. P. Davis A" K [73] Assignee Western Electric Company,Incorporated omeys w M am and R P New York, N.Y. I

ABSTRACT: Logic circuitry is utilized to monitor the coni LOGICCIRCUITRY FOR MONITORING THE tlnued cyclic operation of a pair ofdevices, e.g., strand-feed- CYCUC OPERATIONS OF A PAIR OF DEVICES lngdevices. As the devices functlon a pair of trains of pulses 9 Cl i 3 Din n are generated and the logic circuit detects and generates a a raw 8malfunction signal upon the generation of two pulses within [52] 0.8. CI328/120, one train without the intervening generation of a pulse in the307/216 other train. The logic circuit accepts concurrent generation of[51] lnt.Cl H03k 5/18 pulses, and the subsequent reversal of the leadpulse in the [50] Field of Search... 328/120, trains without thegeneration of malfunction signals. Facilities 119, 130, 106, 109, 63;307/216, 215, 232 are also provided to allow the devices to commenceoperation independent of control by the logic circuits. [56] ReferencesCited UNITED STATES PATENTS 3,327.226 6/1967 Noumey 328/109 I //2 I IPULSE +45) PULSE 72 /0/ START- I GENERATING If LOGIC -39 I INTERRUPTI 1CIRCUIT-4| I l 1 I I l I I 1 I 1 I 1 l l I I I l 1 I93 I I l I 1 I I I I92 i I I r I l I I 1 l- I I T g T I I r L. l J [04 PATENTEnnuvaolsn3,624 522 SHEET 1 BF 3 PATENTED NUVBO I97! LOGIC CIRCUITRY FORMONITORING THE CYCLIC OPERATIONS OF A PAIR OF DEVICES BACKGROUND OFINVENTION 1. Field of Invention This invention relates to methods andsystems for checking the alternate or concurrent generation of pulses intwo trains of pulses. and more particularly, to determining thecontinuity of two series of pulses generated in response to the rotationof a pair of strand-guiding pulleys.

2. Technical Considerations and Prior Art In many manufacturingoperations, it becomes necessary to check the concurrent or alternateoperation of a number of cyclically operating instrumentalities. Onesuch manufacturing operation involves the twisting of wire pairs whichare subsequently fabricated into multiwire, twisted pair cables.Obviously, during the simultaneous or sequential twisting of a number ofpairs of wire, constant vigilance must be exercised by an attendingoperator to detect breaks in the wires being twisted. Inasmuch as thewires are advancing and the twisting facilities are rotating, detectionof the broken wires becomes extremely difiicult. In the situation wherea number of wire pairs are being simultaneously twisted in a machine orin a complex of machines, the problem is further compounded in that manyof the twisting facilities are not readily visible to the attendingoperator.

Manifestly, the manufacture of twisted wire cables will be enhanced iffacilities could be provided to apprise the attending operator of breaksin the individual wires. In addition, manufacture of the twisted pairsof wire will be enhanced if the facilities were capable of inten'uptingthe operation of the twisting machine upon detection of a break in awire.

In monitoring the cyclic alternate and/or concurrent operation of thesemanufacturing instrumentalities, it would be expedient to provideelectrical circuitry that produces indicating and/or control signalsupon the occurrence of a malfunction or interruption of the cyclicoperation of one of the instrumentalities. In the past, systems havebeen provided to check the difference in frequency of two alternatingpulse trains generated in response to the operation of two photoelectricor inductive devices monitoring the functioning of a pair of cyclicallyoperated devices. These systems have included logic detectors to producean output upon the generation of two pulses within one train without thegeneration of an intervening pulse in the other train. These logicdetectors also produce an output signal upon the concurrent generationof pulses in both trains. However, there is still a need to provide amonitoring or logic circuit that will only produce a malfunction outputsignal in response to the nonaltemate and nonconcurrent generation ofpulses in both pulse trains. Further, this monitoring circuit shouldinclude facilities for eliminating spurious responses to locallygenerated or induced noise signals.

In these prior art systems, the functioning of the logic detectordepends upon a first pulse train always leading a second pulse train byone pulse; that is, a pulse is generated in the first train and then apulse is generated in the second train whereafter a pulse is alwaysfirst generated in the first train and then the alternate or secondpulse is generated in the second train. In many practical applications,it is desirable to have a system that will accommodate some fiuctuatioriin the generation of pulses such as a switching back and forth of theleading pulses in the first and second trains. In such a system, pulseswill be generated alternately in the first train and then in the secondtrain, then there will be a period where there will be concurrentgeneration of pulses, and finally there will be a period where a pulseis generated first in the second train and then in the first trainwhereafter the second train leads the first train. With this type ofsystem, the logic detector should only produce an output or malfunctionsignal when two pulses are generated in one train without the generationof an alternate or intervening pulse in the other train to allow for alimited variance in the operation of the monitored instrumentalitieswhich are initiating the generation of the pulse trains.

SUMMARY OF THE INVENTION The present invention contemplates a logiccircuit that functions to check the relative generation of pulses in apair of pulse trains which pulse trains are generated by the continuedoperation of a pair of instrumentalities in a manufacturing facilitysuch as a two-wire twistor. The logic circuit includes a pair of logicdevices having the capability of producing a malfunction signal onlywhen two pulses are generated in one train without the concurrent orintervening generation of a pulse in the other train. Upon operation ofeither one of the logic devices, the malfunction signal is generatedwhich is indicative of the interruption of the operation of one of theinstrumentalities and this signal may be utilized to interrupt furtheroperation of the manufacturing facility.

More particularly, as each pulse is generated,it is shaped and monitoredto produce pulses that are truly representative of the continuedoperation of the manufacturing facility. If spurious noise or low levelextraneous signals are produced or induced in the system they areeliminated. Each logic device is constructed and arranged so that afirst stage in each device is operated by the trailing extremity of eachapplied pulse and a second stage is only operated by the trailingextremity of an output pulse from the first stage. As each pulse isapplied to a logic device, the same pulse is also applied to a resetcircuit associated with the other logic device so as to reset this otherlogic device to an initial set condition. It may be thus appreciatedthat so long as pulses are alternately or concurrently generated in bothpulse trains, neither logic device will be operated thus indicatingcontinued, proper operation of both manufacturing instrumentalities.Inasmuch as the logic circuit does not produce a malfunction signal whenconcurrent pulses are applied, then following the reception ofconcurrent pulses, the alternate periodic generation of pulses in thetwo trains may be reversed or the alternate generation may continue inthe original sequence.

DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of a pair ofstrand feeding and twisting facilities together with a showing of a pairof pulsegenerating devices and logic circuits for monitoring thestrand-feeding operation in accordance with the principles of theinvention;

FIG. 2 is a circuit diagram of a logic and control system responsive toa pair of pulse trains for generating a malfunction signal upon failureof one of the strand feeding and twisting facilities shown in FIG. I;and

FIG. 3 is a pulse-timing diagram illustrating the relationship betweenvarious pulses generated in two trains by the circuit shown in FIG. 2during normal monitoring of the strand feed.

GENERAL DESCRIPTION In order to illustrate the principles of theinvention, attention is first directed to FIG. I, wherein there is shownfacilities for monitoring the continuous feed of a pair of strands orwires 10 and 11 into a strand twistor 12 where the strands are wrappedone around the other. As the strands advance from supply reels l3 and14, the strands engage and rotate a pair of freely mounted idler pulleysI6 and 17. The strands may make a convolution or two about the pulleysto insure that the pulley rotate with the advancing strands. Mounted onthe sides of the pulleys l6 and 17 are a pair of light-reflectingelements I8 and 19 positioned to cyclically move into the path of lightbeams 21 and 22 emanating from light sources 23 and 24. As a result oftheimpingement of the light beams, light flashes 26 and 27 are reflectedonto photosensitive devices 28 and 29. These photosensitive devices maybe active elements that cause the generation of pulses or they may belight-sensitive passive elements such as photoconductive resistors,which will control the generation of pulses. The reflective elements areangularly ofi'set to each other on the respective axis of the pulleys I6and 17 so that the light flashes and the resultant pulses are generatedin alternating pulse trains 31 and 32 (see also FIG. 3).

The output from the photosensitive devices 28 and 29 are applied to apair of pulse-shaping and noise elimination circuits 33 and 34 so thatthe rectangular pulses 36 and 37 (see also FIG. 3) are produced whichare truly representative of the cyclic operation of the pulleys 16 and17 and thus are indicative of the advance of the strands and l 1.

It is to be understood that pulse-generating devices may be utilizedother than photoresponsive devices, for example, angularly offsetmechanical switches that are cyclically closed upon each revolution ofthe pulleys, angularly offset magnetic slugs inserted in the side of thepulleys to actuate magnetic pickup devices, etc. In the alternative, thepulleys may be provided with slots which are angularly ofi'set withrespect to each other to cyclically interrupt light beams impressed onthe pulleys to effectuate the generation of light flashes which may beimpinged on photodiodes to cause the generation of the alternatingtrains of pulses.

The pulse trains 36 and 37 are impressed on a logic circuit generallydesignated by the reference numeral 39 to control an output device 41which will provide signals indicative of the interruption of either thepulse train 36 or the pulse train 37, and thus an indication of theinterruption of the advance of strands 10 or 11. The signal generated bydevice 41 is impressed over a lead 42 to actuate interrupter facilitiescontained within the twistor 12.

The logic circuit 39 is designed to produce an output only upon thegeneration of two pulses within one of the trains 36 or 37 and thefailure to produce a pulse in the other train 36 or 37. The circuit alsohas the capability of continuing to block the pulse trains 36 and 37upon the concurrent generation of pulses in the trains 36 and 37. Infact, following the concurrent generation of pulses, the alternatingsequence in the trains 36 and 37 may be reversed and still the logiccircuit will block these pulses.

DETAILED DESCRIPTIONPULSE GENERATING CIRCUIT Referring to FIG. 2, itwill be noted that the light sources 24 and 23 cyclically reflect lightflashes in an alternating sequence on light-sensitive devices 28 and 29in the form of photoconductive resistors. As light falls on theseresistors, the resistance values alternately drop so that positive-goingpulses are impressed alternately on leads 46 and 47. The pulses arepositive going because a positive potential voltage source 45 isconnected through the resistors 28 and 29 and these resistors arecyclically and alternately decreasing in value upon the impingement ofthe light flashes. The shape of these pulses is illustrated in FIG. 3and are designated pulse forms 31 and 32.

PULSE SHAPING CIRCUIT Considering pulses 31 and 32, it is desirous thatthese pulses be shaped to have a rectangular configuration and, further,that these pulses be free of any noise or spurious signals. Each pulse31 is impressed on a low-pass filter circuit comprising a resistor 48and a capacitor 49. If an applied pulse is a spurious spike of shortduration, the pulse will not act to charge the capacitor 49 to a valuenecessary to operate a transistor device 51 which comprises a pair ofseries transistors 52 and 53 connected as a Darlington pair. If thespurious signal is of a low value, then it is incapable of raising thepotential at a junction 54 and, as a result, the transistor device 51 isnot operated. The potential level of junction 54 is controlled byvoltage-divider network, including the photoconductive resistor 28 and aresistor 56 connected to an adjustable potentiometer 57.

Assume that a pulse 31 arrives that is of sufficientlevel and duration,then capacitor 49 accumulates sufficient charge to control theimpression of a positive-going potential condition on the base of thetransistor 52 to initiate conduction of both transistors 52 and 53.Conduction of these transistors results in a sharp drop in thecontroller collector potentials which will be maintained until thetransistors 52 and 53 are cut 011' due to a sufficient drop in potentialof the trailing extremity of the applied pulse 31. As a result of thisoperation, a negative-going, rectangular-shaped pulse is impressed onthe base of a NPN- transistor buffer amplifier 58.

In a like manner, pulses produced by the impingement of light and thephotoresistor 29 is impressed on a second Darlington pair 61 associatedagain with a low-pass filter comprising resistor 62 and capacitor 63, aswell as a voltage level control comprising the photoconductive resistor29 connected through junction 64 to a resistor 65 connected to anadjustable potentiometer 66. Also associated with the output of theDarlington pair 61 is a second NPN-transistor buffer amplifier 67.Outputs of the amplifiers 58 and 67 are normally positivegoingrectangular-shaped pulses 36 and 37 which are applied alternately to thelogic circuit generally designated by the reference numeral 39.

LOGIC CIRCUITS The logic circuit .39 is arranged to monitor thealternate application of pulses 36 and 37. If the pulses are alternatelyor concurrently impressed on the logic circuit, the pulses areeffectively blocked to preclude the operation of the outputresponsivedevice 41. The logic circuit also has the capability of continuing theblocking operation in the situation where there is a reversal in thetiming sequence of the application of the impressed pulses 36 and 37following the impression of one or more sets of concurrent pulses 36 and37.

Considering pulses 36, these pulses are impressed on a logic devicecomprising a pair of bistable multivibrators 71 and 72. Themultivibrators are interconnected together by a coupling 73 so that twocomplete operations of the multivibrator 71 results in a singleoperation of the multivibrator 72. Associated with the multivibrators 71and 72 is a NAND-gate 74 which under prescribed conditions impresses areset signal on lead 76 to restore both multivibrators to an initialcondition. Further, each multivibrator 71 or 72 is designed to respondonly to the trailing extremity of an applied pulse. Multivibrators 71and 72 are commercially available and are known as J-K flip-flops. Suchflip-flop circuits may be fabricated as an integrated circuit, one suchcircuit is manufactured by the Motorola Company and is disclosed on page5-34 through 5-38 of their INTEGRATED CIRCUIT DATA BOOK dated Aug. 1968.

The input of the multivibrator 71 receives the pulses 36 and this inputis associated with a capacitor 77 which functions to dissipate shortspurious spikclike noise signals that are impressed or induced in thesystem. In an initial condition, the output impressed on the coupling 73is at a low potential level. Upon application of the trailing extremityof the pulse 36, the two stages within the multivibrator 71 change stateso that a positive-going potential condition is impressed on thecoupling 73. The first stage of the multivibrator 72 will not respond tothis increase in potential, but will only respond upon a subsequent dropin potential on the coupling. The second or output stage of themultivibrator stage of the multivibrator 72 is normally at a highpotential level which is impressed over a lead 78 to a first input ofthe NAND-gate 74. The output of the NAND gate impressed on lead 76 isinitially at a high potential and is ineffective to control theresetting of multivibrators 71 and 72. If the NAND gate is operated sothat the output switches to a low potential, then both multivibrators 71and 72 are reset to the initial condition. The ap pearance of a lowpotential on the lead 76 controls the multivibrators 71 and 72 so thatthey are nonresponsive to any changes in potential applied to theirfirst input stages.

If following the impression of a pulse 36 there is a pulse 37 generated,this pulse is impressed over a lead 79 to the other input of theNANDsgate 74. The impression of high potentials over the leads 78 and79results in the operation of the NAND gate to drop the potential appliedto the lead 76 and, as a result, the multivibrators 71 and 72 are reset.If the pulse 37 is concurrently produced at the same time that the pulse36 is impressed on the input stage of the multivibrator 71, the

NAND gate will again function to reset or to hold the multivibrator 71in the initial condition. In effect, presence of a low potential on thelead 76 overrides the efiect of any change in potential applied to theinput or first stages of the multivibrators 71 and 72.

Considering now the application of the pulses 37, they are applied to a.l-K flip-flop circuit comprising multivibrators 81 and 82interconnected by a coupling 83. Associated with these multivibrators isa second NAND-gate 84 which functions to control the reset of themultivibrators 81 and 82 by controlling the potential impressed on alead 86. Again, a capacitor 87 is provided to dissipate spurious short,spikelike noise signals. The second or output stage of the multivibrator82 is connected over lead 88 to the second input of the NAND-gate 84. Inaddition, pulses 36 are impressed over a lead 89 to act in conjunctionwith the potential impressed on lead 88 to control the NAND-gate 84. Insummary, it may be appreciated that the logic circuit associated withthe impressed pulses 37 is identical with the logic circuitry associatedwith the impressed pulses 36.

The logic device associated with the pulse trains 36 and 37 areeffective to perfonn their blocking function upon a reversail in thetime sequence in the applied pulses 36 and 37 following the applicationof concurrent pulses 36 and 37 to the multivibrators 71 and 81. Moreparticularly, assume first that the pulses 36 are leading the pulses 37and that the sequence of pulses 37 gradually increase so that concurrentpulses 36 and 37 are impressed on the multivibrators 71 and 72. Aspreviously explained, the concurrent application of pulses results inthe operation of both NAND-gates 74 and 84 to reset all of themultivibrators. If the frequency of pulses 37 increases so that pulses37 now lead pulses 36, then the logic circuits will reverse their cyclicoperation and continue to block the pulses in the new time sequence solong as the pulses 37 and 36 are alternately impressed.

If, however, a situation arises where two pulses in either pulse trainare generated and impressed on either of the multivibrators 71 or 81,without the intervening generation and impression of a pulse in theother train, there is a second change in potential impressed on thecoupling 73 or 83 to change the operating states of the stages in eitherthe multivibrators 72 or 82. As a result, there is a drop in potentialimpressed on either lead 78 or 88 which functions to interrupt theoperation of the NAND-gate 74 or 84. This drop in potential impressed oneither lead 78 or 88 is also utilized to control the generation of asignal which may be used to interrupt the operation of the monitoredinstrumentality, such as the twistor 12.

It will be recalled that under normal operating conditions, thepotential on leads 78 and 88 are at a high value. These high potentialsare applied to a NAND-gate 91. The output of the NAND gate is normallyat a low level which is impressed on a NAND-gate 92 which functions toinvert the applied voltage so that its output potential is high. Thishigh potential is also impressed on an input to the NAND-gate 91. Uponany one of the inputs to the NAND-gate 91 changing from a high value toa low value, the NAND gate will function so that an increased potentialis applied on an output lead 93. It may be thus appreciated that achange in potential impressed on either lead 78 and 88 due to theoperation of the second stages of either the multivibrators 72 and 82will result in an operation of the NAND-gate 91. Upon operation of theNAND-gate 91, the output potential goes to a high value which isimpressed on the NAND-gate 92 to invert its output and impress a lowpotential on the NAND-gate 91, thus, locking the NAND-gate 91 to impressa continual high potential condition on the output lead 93.

START-INTERRUPT CIRCUIT The high potential output impressed on lead 93from the NAND-gate 91, indicative of a malfunctioning of one of thestrand-feeding operations, is used to control facilities which functionto interrupt further operation of the strand twistor. Under normaloperating conditions, the potential at the output of the NAND gate is ata low level and current flows from the energy source 45 over a lead 101through a coil of a relay 102, over the lead 93 to the output of theNAND-gate 91. When the NAND-gate 91 switches so that the output is high,then high potential conditions are applied to both ends of the coil ofthe relay 102 and, as a result, current ceases to flow. The relay 91 isthus deenergized to open contacts 104 con nected in an energizationcircuit for a heavy duty relay 106. Deenergization of relay 106 resultsin the opening of contacts 107 contained in a power control circuit forthe twistor 12, thereby interrupting further operation of the twistor.Deenergization of the relay 106 also allows contacts 108 to closecompleting an energization circuit to a signal glow tube 109 whichilluminates to apprise an attending operator that there has been a breakin one or the other of the strands 10 or 11.

Upon repair of the strand break or upon an initial start up of thetwistor, it may be necessary to bypass the logic circuit 39 until thetwistor is brought up to a normal operating speed. During the initialstartup period, there will be abnormal fluctuations in the strand feed,thus, if the logic circuit 39 is connected to monitor the pulse trains,there is a good possibility that a false indication of strand breakwould be detected to operate the interrupt circuit. Further, during theinitial startup period, it is necessary to erase any previous memorythat may exist in any of the modules of the logic circuit 39.

Initiation of the operation of the twistor 12 is attained by momentarilydepressing a start button 111 to apply positive potential from thesource 45, over a lead 112, through the coil of a relay 113, through adiode 114 to a collector of a NPN- transistor 116. This positivepotential is also impressed through a resistor 115 to a base of thetransistor 116. Inasmuch as the emitter of the transistor 116 isconnected to ground, this transistor is biased into a state ofconduction. Conduction of transistor 116 is accompanied by anenergization of the relay 113 which closes contacts 118 to complete abypass-locking circuit to the source of energy 45. Closure of thecontact 118 completes an added path for the current to the base of thetransistor 116.

Conduction of transistor 116 completes an energizing circuit for therelay 102, which may be traced from source 45, over lead 101, throughthe coil of relay 102, through a diode 119, through conductingtransistor 116 to ground. Energization of relay 102 draws up contacts104 to energize relay 106 which functions to close contacts 107 in thepower circuit for the twistor 12.

This auxiliary start circuit is maintained energized for a sufficientperiod of time to enable the twistor to advance to a normal operatingspeed. More specifically, conduction of transistor 116 is alsoaccompanied by a charging of a capacitor 121 through the resistor 117.After a period of time, determined by the time constant of the resistor117-.capacitor 121 and sufiicient to enable the twistor 12 to assumenormal operating speed, the capacitor 121 accumulates sufficient chargeto apply a firing potential to an emitter electrode of a unijunctiontransistor 122. Firing of transistor 122 applies the potential ofcapacitor 121 across the base-emitter circuit of the transistor 116causing this transistor to be rendered nonconductive thereby releasingthe relay 113. During this period of time, set by the values of theresistor 117 and the capacitor 121, the twistor- 12 advances to theoperating speed and alternating pulse trains 31 and 32 will be generatedto set the various modules of the logic circuit in a proper state forsubsequent detection of malfunctions in the feed of the strands 10 and11.

It will be noted that the energizing circuit for the relay 106 isprovided with a manual switch 123 to enable operation of the twistor 12independent of control by the logic circuit 39.

SUMMARY or OPERATION Recapitulating on the operation of the system,attention is directed to FIG. 3 which will be considered in conjunctionwith H68. 1 and 2. As the strands 10 and 11 continually adva'nce,alternating trains and pulses 31 and 32 are generated. These pulses arereshaped by circuits 33 and 34 into rectangular-shaped pulses 36 and 37.Each pulse 36 is applied to the logic circuit and the trailing extremityof each of these pulses switches the operating states of themultivibrator 71 to impress an increased potential condition on thecoupling 73. Following application of a pulse 36, a pulse 37 isimpressed on the NAND-gate 74 to drop the potential appearing on thelead 76 to reset the multivibrator 71 to the initial state. As a result,there is no change in potential impressed on the lead 78. In a likemanner, the alternate impression of pulses 37 and 36 on themultivibrator 81 and NAND-gate 84 are ineffective to change the outputpotential impressed on the lead 88.

Now assume that there is a break in strand 11 so that pulses 31 aregenerated at a constant rate while pulses 32 are generated at aprogressively slower rate. It will be noted that when pulses 31 and 32'are generated concurrently, the multivibrator 71 is still reset prior tothe impression of a second pulse 36 so that the multivibrator 72 is notoperated. However, as the rate of generation of the pulses 32 continuesto decrease there will come a time when two pulses 31" are generatedwithin the period of time that two pulses 32" are generated. Thesuccessive appearance of two pulses 36'' cffectuates a double operationof the multivibrator 71 so that a trailing extremity of a pulseimpressed on the coupling 73 is impressed on the multivibrator 72 tochange its states of operation whereupon the potential impressed on thelead 78 drops. The drop in potential on the lead 78 is effective tocontrol the NAND-gate 91 to impress an increased potential on the outputlead 93. The increased potential on lead 93 is effective to interruptthe energization of the relay 102 whereupon the relay 106 is deenergizedto open contacts 107 to thereby interrupt the power circuit for thetwistor 12. At this time the contacts 108 close to illuminate the glowtube 109 to apprise the attending operator that there has been a breakin one of the strands.

It is to be understood that the abovedescribed arrangements of circuitsand construction of elemental modules are merely illustrative of theinvention and that many other modifications may be made withoutdeparting from the invention.

What is claimed is:

1. In an apparatus for ascertaining the continuity of a pair of trainsof pulses,

a pair of logic devices, each having two bistable circuits coupledtogether for successive operation upon application of two pulses to afirst bistable circuit of a device,

means associated with each device for resetting the first bistablecircuit to preclude the operation of the second bistable circuit,

means for applying the two trains of pulses individually to the devicesto successively operate the first bistable circuit in each device, I

means for applying each pulse to operate the resetting means associatedwith the device receiving the pulses from said other train, and

means responsive to successive operation of two bistable circuits in adevice for generating a signal indicative of noncontinuity of the pulsesin the pair of trains.

2. In a system for monitoring two trains of pulses wherein the pulses inthe respective trains are alternately generated;

means responsive to said pulses for shaping said pulses into pulseshaving a righbangular trailing extremity,

first means responsive to the impression of two successive trailingextremities of pulses in the first train for producing an output signal,

second means responsive to the impression of two successive trailingextremities of pulses in the second train for producing an outputsignal, and

means responsive to the alternate generation of pulses in the first andsecond trains without the generation of a intervening pulse foroverriding the effect of the impression of the trailing extremities ofsaid pulses to said first and second means to block the generation of anoutput signal.

3. In a system for monitoring the alternate generation of pulses in apair of pulse trains,

a logic circuit responsive to two successive application of pulses inthe first train for generating an output signal, said logic circuitcomprises a pair of bistable multivibrators interconnected together tooperate a first of said multivibrators upon application of the trailingedge of a pulse in the first train, and to operate a second saidmultivibrator upon application of the trailing edge of a pulse generatedby two operations of the first multivibrator,

a gating circuit having two inputs for generating an output to resetboth multivibrators to the initial condition;

means for applying the output of the second multivibrator to one of saidgating circuit inputs to condition said gating circuit for operation;and

means for applying each pulse in the second train to the other input ofsaid gating circuit to cyclically reset said first multivibrator to aninitial condition while holding said second multivibrator fromoperation.

4. In an apparatus for ascertaining the continuity of a pair of trainsof discrete pulses, wherein the individual pulses are generatedalternatively or concurrently in one train of pulses with the individualpulses generated in the other train of pulses,

a pair of devices, each having a pair of pulse-responsive bistable unitsthat change state upon the receipt of the trailing extremity of a pulse,each pair of pulse-responsive bistable units being coupled together tooperate the second bistable unit upon completion of two successiveoperations of the associated first bistable unit,

means for applying individual trains of pulses to individual devices tosuccessively operate the first bistable units in said devices,

means associated with each device for resetting the first bistable unitin each device,

means responsive to the successive operation of two bistable units in adevice for generating a signal indicative of the noncontinuity of thetrain pulses applied to one of the devices, and

means for applying the pulses in each train to the resetting meansassociated with the device receiving the other train of pulses tocyclically reset said first devices upon al temate or concurrentapplication of pulses from said trains to said devices.

5. In a system for monitoring a pair of trains of pulses wherein thepulses are (l) alternately generated with pulses in a first trainleading the pulses in the second train, (2) concurrently generated, and(3) then alternately generated with the pulses generated in the secondtrain leading the pulses in the first train;

a first means responsive to the successive impression of two pulses inthe first train without the generation of a pulse in the second trainfor producing an output signal;

a second means responsive to the successive impression of two pulses inthe second train without the generation of a pulse in the first trainfor producing an output signal;

normally unoperated means associated with each of the pulse-responsivemeans for resetting said pulse-responsive means to block the generationof an output signal; and

means responsive (l) to the alternate generation of pulses in the firstand then the second trains (2) to the concurrent generation of pulses inthe first and second trains, and (3) to the alternate generation ofpulses in the second and then the first train for operating saidresetting means to block the production of an output signal.

6. ln a system for checking the alternate generation of pulses in afirst series with the generation of pulses in a second se-- ries;

a pair of devices each having an input bistable unit and an outputbistable unit. each input bistable unit responding to the trailingextremity of a pulse for changing its state of operation, and eachoutput bistable unit responding to two changing states of operation ofthe associated input bistable unit for changing its output from aninitial potential level to a second potential level;

means for applying the two series of pulses to the input bistable unitsin the respective devices;

means coupled to each of said devices and responsive to the initialpotential level of the associated output bistable unit and theapplication of a pulse applied to the other first unit for resettingeach respective device to an initial condition; and

means responsive to the application of a pair of pulses to one of saidfirst bistable units to operate the second bistable unit without theintervening application of a pulse to the other first bistable unit forproducing a signal indicative of the nonaltemate application of pulsesto said first units.

7. In a system for comparing the frequency of a first series of pulseswith the frequency of a second series of pulses;

a first pair of pulse-responsive bistable units interconnected togetherthrough an output on the first unit and a input on the second unit, saidunits having two states of stable operation and said second unitoperative to change its state of operation upon two changes in the stateof operation of the first unit;

a second pair of pulse-responsive bistable units identical to said firstpair of pulse-responsive bistable units;

a first gating circuit responsive to two input control signals forresetting said first pair of pulse-responsive units to an initial stateof operation;

a second gating circuit responsive to two input control signals forresetting said second pair of pulse-responsive units to an initial stateof operation;

means for applying the output of the second unit in said first pair toimpress a first control signal on said first gating circuit;

means for applying the output of the second unit in said second pair toimpress a first control signal on said second gating circuit;

means for applying the first series of pulses on said first unit of saidfirst pair of units to successively change the state of operation ofthis unit;

means for applying the second series of pulses on said first unit ofsaid second pair of units to successively change the state of operationof this unit;

means for applying the first series of pulses to impress second controlsignals on said second gating circuit to successively reset said secondpair of units;

means for applying the second series of pulses to impress second controlsignals on said first gating circuit to suecessively reset said firstpair of units; and

means responsive to successive operations of a first unit in either pairand the operation of the associated second unit for indicating theoccurrence of the impression of successive pulses to one of said firstunits without the application of a pulse to the other first unit in saidother pair.

8. A method of checking the alternate generation of pulses in a firstseries with the generation of pulses in a second series, wherein theseries of pulses are respectively applied to a pair of two-unitpulse-responsive devices, the first unit in each pair being susceptableof changing state upon impression of the trailing extremity of eachpulse and the second unit in each pair being susceptable of changingstate upon two changes in state of the first unit, the improvement whichcomprises the steps of;

applying the two series of pulses to first units in the respec tivepulse-responsive devices to change alternately the state of operation ofthe respective first units; applying in the output of a second unit inone of the devices in conjunction with the pulse applied to the firstunit in the other device to reset each operated first unit to an initialstate; and

generating an output signal from two successive operations of eitherfirst unit and the subsequent operation of the associated second unitupon nonapplication of a pulse to the first unit of the other device.

9. A method of checking the alternate generation of pulses in a firstseries with the generation of pulses in a second series, wherein theseries of pulses are respectively applied to a pair of two-unitpulse-responsive devices, the first unit in each pair being resetableand being susceptible of changing state upon impression of the trailingextremity of each pulse and the second unit in each pair beingsusceptible of changing state upon two changes in state of the firstunit, the improvement which comprises the steps of:

impressing one series of pulses to both first units of eachpulse-responsive device to change the state of one unit and reset theother unit to an initial state;

impressing the other series of pulses to both first units of eachpulse-responsive device to change the state of the other unit and resetthe one unit to an initial state; and generating an output signal fromtwo successive changes in state of either first unit without anintervening reset and the subsequent change in state of the associatedsecond unit.

I t t i l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,62L.,522 Dated .4 November- 30, 1971 John J. Glosek Patent No.

lnvent0r(s) l: is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

T Column 3, line 73, "controller" should be deleted.

Column 10, line 23, "in the" should be --an--.

Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. In an apparatus for ascertaining the continuity of a pair of trainsof pulses, a pair of logic devices, each having two bistable circuitscoupled together for successive operation upon application of two pulsesto a first bistable circuit of a device, means associated with eachdevice for resetting the first bistable circuit to preclude theoperation of the second bistable circuit, means for applying the twotrains of pulses individually to the devices to successively operate thefirst bistable circuit in each device, means for applying each pulse tooperate the resetting means associated with the device receiving thepulses from said other train, and means responsive to successiveoperation of two bistable circuits in a device for generating a signalindicative of noncontinuity of the pulses in the pair of trains.
 2. In asystem for monitoring two trains of pulses wherein the pulses in therespective trains are alternately generated; means responsive to saidpulses for shaping said pulses into pulses having a right-angulartrailing extremity, first means responsive to the impression of twosuccessive trailing extremities of pulses in the first train forproducing an output signal, second means responsive to the impression oftwo successive trailing extremities of pulses in the second train forproducing an output signal, and means responsive to the alternategeneration of pulses in the first and second trains without thegeneration of a intervening pulse for overriding the effect of theimpression of the trailing extremities of said pulses to said first andsecond means to block the generation of an output signal.
 3. In a systemfor monitoring the alternate generation of pulses in a pair of pulsetrains, a logic circuit responsive to two successive application ofpulses in the first train for generating an output signal, said logiccircuit comprises a pair of bistable multivibrators interconnectedtogether to operate a first of said multivibrators upon application ofthe trailing edge of a pulse in the first train, and to operate a secondsaid multivibrator upon application of the trailing edge of a pulsegenerated by two operations of the first multivibrator, a gating circuithaving two inputs for generating an output to reset both multivibratorsto the initial condition; means for applying the output of the secondmultivibrator to one of said gating circuit inputs to condition saidgating circuit for operation; and means for applying each pulse in thesecond train to the other input of said gating circuit to cyclicallyreset said first multivibrator to an initial condition while holdingsaid second multivibrator from operation.
 4. In an apparatus forascertaining the continuity of a pair of trains of discrete pulses,wherein the individual pulses are generated alternatively orconcurrently in one train of pulses with the individual pulses generatedin the other train of pulses, a pair of devices, each having a pair ofpulse-responsive bistable units that change state upon the receipt ofthe trailing Extremity of a pulse, each pair of pulse-responsivebistable units being coupled together to operate the second bistableunit upon completion of two successive operations of the associatedfirst bistable unit, means for applying individual trains of pulses toindividual devices to successively operate the first bistable units insaid devices, means associated with each device for resetting the firstbistable unit in each device, means responsive to the successiveoperation of two bistable units in a device for generating a signalindicative of the noncontinuity of the train pulses applied to one ofthe devices, and means for applying the pulses in each train to theresetting means associated with the device receiving the other train ofpulses to cyclically reset said first devices upon alternate orconcurrent application of pulses from said trains to said devices.
 5. Ina system for monitoring a pair of trains of pulses wherein the pulsesare (1) alternately generated with pulses in a first train leading thepulses in the second train, (2) concurrently generated, and (3) thenalternately generated with the pulses generated in the second trainleading the pulses in the first train; a first means responsive to thesuccessive impression of two pulses in the first train without thegeneration of a pulse in the second train for producing an outputsignal; a second means responsive to the successive impression of twopulses in the second train without the generation of a pulse in thefirst train for producing an output signal; normally unoperated meansassociated with each of the pulse-responsive means for resetting saidpulse-responsive means to block the generation of an output signal; andmeans responsive (1) to the alternate generation of pulses in the firstand then the second trains (2) to the concurrent generation of pulses inthe first and second trains, and (3) to the alternate generation ofpulses in the second and then the first train for operating saidresetting means to block the production of an output signal.
 6. In asystem for checking the alternate generation of pulses in a first serieswith the generation of pulses in a second series; a pair of devices eachhaving an input bistable unit and an output bistable unit, each inputbistable unit responding to the trailing extremity of a pulse forchanging its state of operation, and each output bistable unitresponding to two changing states of operation of the associated inputbistable unit for changing its output from an initial potential level toa second potential level; means for applying the two series of pulses tothe input bistable units in the respective devices; means coupled toeach of said devices and responsive to the initial potential level ofthe associated output bistable unit and the application of a pulseapplied to the other first unit for resetting each respective device toan initial condition; and means responsive to the application of a pairof pulses to one of said first bistable units to operate the secondbistable unit without the intervening application of a pulse to theother first bistable unit for producing a signal indicative of thenonalternate application of pulses to said first units.
 7. In a systemfor comparing the frequency of a first series of pulses with thefrequency of a second series of pulses; a first pair of pulse-responsivebistable units interconnected together through an output on the firstunit and an input on the second unit, said units having two states ofstable operation and said second unit operative to change its state ofoperation upon two changes in the state of operation of the first unit;a second pair of pulse-responsive bistable units identical to said firstpair of pulse-responsive bistable units; a first gating circuitresponsive to two input control signals for resetting said first pair ofpulse-responsive units to an initial state of operAtion; a second gatingcircuit responsive to two input control signals for resetting saidsecond pair of pulse-responsive units to an initial state of operation;means for applying the output of the second unit in said first pair toimpress a first control signal on said first gating circuit; means forapplying the output of the second unit in said second pair to impress afirst control signal on said second gating circuit; means for applyingthe first series of pulses on said first unit of said first pair ofunits to successively change the state of operation of this unit; meansfor applying the second series of pulses on said first unit of saidsecond pair of units to successively change the state of operation ofthis unit; means for applying the first series of pulses to impresssecond control signals on said second gating circuit to successivelyreset said second pair of units; means for applying the second series ofpulses to impress second control signals on said first gating circuit tosuccessively reset said first pair of units; and means responsive tosuccessive operations of a first unit in either pair and the operationof the associated second unit for indicating the occurrence of theimpression of successive pulses to one of said first units without theapplication of a pulse to the other first unit in said other pair.
 8. Amethod of checking the alternate generation of pulses in a first serieswith the generation of pulses in a second series, wherein the series ofpulses are respectively applied to a pair of two-unit pulse-responsivedevices, the first unit in each pair being susceptable of changing stateupon impression of the trailing extremity of each pulse and the secondunit in each pair being susceptable of changing state upon two changesin state of the first unit, the improvement which comprises the stepsof; applying the two series of pulses to first units in the respectivepulse-responsive devices to change alternately the state of operation ofthe respective first units; applying in output of a second unit in oneof the devices in conjunction with the pulse applied to the first unitin the other device to reset each operated first unit to an initialstate; and generating an output signal from two successive operations ofeither first unit and the subsequent operation of the associated secondunit upon nonapplication of a pulse to the first unit of the otherdevice.
 9. A method of checking the alternate generation of pulses in afirst series with the generation of pulses in a second series, whereinthe series of pulses are respectively applied to a pair of two-unitpulse-responsive devices, the first unit in each pair being resetableand being susceptible of changing state upon impression of the trailingextremity of each pulse and the second unit in each pair beingsusceptible of changing state upon two changes in state of the firstunit, the improvement which comprises the steps of: impressing oneseries of pulses to both first units of each pulse-responsive device tochange the state of one unit and reset the other unit to an initialstate; impressing the other series of pulses to both first units of eachpulse-responsive device to change the state of the other unit and resetthe one unit to an initial state; and generating an output signal fromtwo successive changes in state of either first unit without anintervening reset and the subsequent change in state of the associatedsecond unit.